An amorphous silicon thin film transistor (TFT) is generally used as an integrated component in a scan shift circuit, and some amorphous silicon TFT elements have a threshold voltage shift (Vth Shift) of instability. With increased time in use, the degree of the threshold voltage shift will seriously affect the normal operation of the scan shift circuit, and finally, even the scan shift circuit will fail.
Nowadays, shift register circuits constructed by the amorphous silicon TFTs will face the condition with increasing time in use, so as to generate the threshold voltage shift phenomenon. With the increase in the severity of the offset, it will also affect the normal operation of the circuit, and even cause the circuit to fail.